Keck: A 10-m Paintbrush

My friend Sebastian shared this awesome image with me today, and was kind enough to let me post it here:

"Focusing Keck" by Sebastian Pineda (Caltech)

This is a screenshot taken from one of the guider cameras on Keck, one of the largest optical telescopes in the world. Each hexagonal cluster of points is actually a single star being focused by each of the mirror segments! The dots are small since each segment is essentially in focus, and Keck has tremendously good "seeing"

Normally each segment of the primary mirror would focus to the exact same location. However the mirrors are slightly (and intentionally) misaligned, allowing the operators to see the focus for each of the 36 primary mirror segments. For comparison, here's one of the Keck primary mirrors in its full glory:

(Copyright W. M. Keck Observatory)

Of course Keck routinely produces stunning images of the cosmos (check some out here!) but I thought this simple black/white image above was amazing. In one image it captures the simplicity and beauty of observational astronomy, while reminding us of the engineering marvel that allowed its creation. It reminds me of the million little things that must go right each night to make astronomy happen.